Which bottom feeder will be compatible with my tetra community tank?

I have a 25 gallon tank with neon tetras,glow light and balloon red eye tetra. My tank has no gravel but just some stones as deco and a plant that grows on a piece of rock. Much food gets aculated on the bottom and none of the tetras seems to care, so I thought of getting a bottom feeder to do the 'cleaning'. Which bottom feeder should I get and how many? Cory, Oto, etc?